Electrical measurement instruments, such as digital multimeters (DMMs), can often be configured to measure a variety of electrical parameters, such as voltage, current, and resistance. Many DMMs are able to switch between various sets of inputs, with each set of inputs or channels supporting most measurement functions of the DMM. Electrical measurement instruments, therefore, typically include an electrical switch for selecting between the various channels.
In some electrical measurement instruments, an external switch may be installed onto a printed circuit board (PCB) for selecting between channels. In other instruments a PCB of the electrical measurement instrument may be configured to form a switch. In general, such a PCB switch comprises a plurality of contacts on a surface of the PCB and one or more conductive springs configured to make electrical contact with one of the respective plurality of contacts when pressed there against. In order to place the electrical measurement instrument in a first state, at least one of the conductive springs is compressed against a first contact formed on the PCB. In order to place the electrical measurement instrument in a second state, the conductive spring is translated to a second position, which for example, presses the conductive spring in contact with a second contact. As the conductive spring moves across the PCB from the first contact to the second contact, the free end of the conductive spring scrapes along the surface of the first and second contacts as well as the PCB. Thus, in such switches, switching from one state to another state may cause wear to the conductive springs therein due to frictional forces applied to the conductive springs. The wear caused to the end of the conductive spring may also potentially damage the contacts and the PCB.